Coil-On-Plug (COP) Boots provide the insulated pathway that delivers high-voltage energy from the ignition coil directly to the spark plug. They seal the connection between the coil and spark plug while protecting against moisture, heat, and voltage leakage. Proper COP boot function ensures stable ignition performance, complete combustion, and reliable engine operation under all driving conditions.
How It Works
- The ignition coil generates high-voltage output needed for spark plug ignition
- The COP boot insulates and directs this voltage safely to the spark plug tip
- The boot maintains a secure physical and electrical seal between coil and plug
- A built-in spring or conductor transfers the coil’s energy to the spark plug electrode
- Proper boot integrity prevents arcing, misfires, and ignition energy loss
Symptoms of a Failing Coil-On-Plug Boot May Include
- Engine misfires under load or during acceleration
- Rough idle or hesitation
- Reduced fuel economy
- Hard starting or intermittent no-start condition
- Illuminated Check Engine Light (CEL)
Product Features & Benefits from Walker Products
- Exact OE Fit – Ensures proper sealing and reliable connection to ignition coil and spark plug
- OE Replacement Quality – Designed to meet or exceed OEM performance standards
- High-Temperature Resistant Materials – Protects against heat, oil, and moisture intrusion
- Precision Conductive Spring – Ensures consistent voltage transfer for optimal spark performance
- Enhanced Dielectric Strength – Prevents arcing, carbon tracking, and misfire conditions
- Restores Ignition Efficiency – Improves engine performance, idle quality, and fuel economy
Common Check Engine Light (CEL) / OBD-II Codes
In accordance with the EPA’s OBD-II standards (adopted in 1996 and later expanded to heavy-duty applications), the following Diagnostic Trouble Codes (DTCs) are commonly associated with ignition coil and COP boot failures.
Use this list as a general reference only. Always consult a qualified technician and follow vehicle manufacturer and EPA guidelines for diagnostics, component replacement, and ECU/PCM relearn procedures.
- P0300 – Random/Multiple Cylinder Misfire Detected
- P0301 – Cylinder 1 Misfire Detected
- P0302 – Cylinder 2 Misfire Detected
- P0303 – Cylinder 3 Misfire Detected
- P0304 – Cylinder 4 Misfire Detected
- P0305 – Cylinder 5 Misfire Detected
- P0306 – Cylinder 6 Misfire Detected
- P0307 – Cylinder 7 Misfire Detected
- P0308 – Cylinder 8 Misfire Detected
- P0350 – Ignition Coil Primary/Secondary Circuit
- P0351–P0362 – Ignition Coil “A” through “L” Primary/Secondary Circuit Faults